Hot corrosion behaviour of 7YSZ + Gd2O3 nano-composites in molten salts prepared by spark plasma sintering

ABSTRACTThis study compares the hot corrosion performance of yttria-stabilised zirconia (7YSZ), and 7YSZ + Gd2O3 composite samples in the presence of molten mixture of Na2SO4 + V2O5 at 1150°C. For 7YSZ, the reaction between NaVO3 and Y2O3 produces YVO4 and leads the transformation of tetragonal ZrO2 to monoclinic ZrO2. A high-density in sintered 7YSZ + Gd2O3 samples, led minor amounts of monoclinic ZrO2 and tetragonal GdVO4 as the hot corrosion products with only traceable amounts of YVO4, and a stable corroded layer was formed. Due to the synergic effect of doping of zirconia with Gd2O3, the 7YSZ + Gd2O3 sample has a much better hot corrosion crack resistance than 7YSZ.